Hint

Answer

9

x= recessive: white
X= dominant: black

A purebred, female, white cat would have the alleles xx for fur color (white). A purebred, male, black cat would have the alleles YX (black).
The possible allele combinations for offspring are as follows (set up a Punnett Square)

Xx......Yx
Xx......Yx

Every female kitten would be black, with a recessive allele for white fur. Every male kitten would be white. There are 9 black kittens, so that means there are 9 female kittens.Hide

Comments

Your first and most likely false assumption is that the genes that impart color are on the same chromosomes as those that impart the sex of the animal. Cats have 38 chromosomes, only two of which impart the sex of the animal. Unfortuately, genetics is not as simple as a recessive and dominate alleles, that's why a brown eyed mother and a blue eyed father can have a green eyed child.

well the mothod is right for humans, but not necesarily correct for animals. there are plenty of multi colored cats to prove this.

As for the sex of the animal a "purebreed" white or black doesn't mean that 100% of it's children will be that color it's just a higher probability ask any breeder that's been doing it for a very long time and they will tell you that it wouldn't be the case for the colors to hold true. out of 12 cats there is a guarentee that 1 will probly be halfwhite/black. the only way for them to turn up true is in a controlled enviroment for many generations.

There is also the ever present random mutation. It guarentees that not all offspring will breed true to the parents

When the pure black and pure white mix, you could end up with almost anything in cats. Tuxedo or even tabby striped orange kitties. Genetics for color in cats is not as set as it is for plants. Even mix two completely different human races and you come up with more of a mix than following one or the other parent.

I just re-read this and the science behind it is MAJORLY FLAWED. With the male being the domiant purebred black cat it would make it where the was a dominant YX for black and a xx for white. all possible combinations are as follows:

Xx, Yx, xX, xY

there will be no white cats following these statements. I have sent a "correction asking to remove this teaser due to the seriously flawed science.

I apologize nothing personal the science is just flawed to make the teaser inacurate.

Actually, the colors are, for the most part, located on the sex chromosomes, the X chromosome to be exact. Thats why only female cats can have mixed colors, because the two different X chromosomes are turned on in different parts of the body.

The genetics of cat coats is very complex. The teaser may be good for people just starting in genetics but anyone with a little knowledge will easily see the flaw.

I don't like to criticise, but to make the teaser better it would have helped if you stated what assumptions you were making in the question. i.e "Assuming that the colour of a cats coat was linked to the X and Y chromosomes ......"

As a bit of trivia, only about 1 in 3000 male cats have a tortoiseshell coat and this may because they have Klinefelter's syndrome (carrying an extra X chromosome), and will almost always be sterile. So if you see a tortoiseshell cat you could always bet a friend it is female, You will almost cirtainly win the bet (at least you will win a lot more than you lose)

For more information visit http://en.wikipedia.org/wiki/Tortoiseshell_cat

I did like this teaser, and I have nothing against it.
However, it's true that the science is flawed. If it were simply a matter of probability, all anomolies and mutations aside, then it would be awesome.
But gender and color are not linked. So just because you have a male black cat and a female white one, it doesn't mean that you can't have a black female or white male. As someone mentioned earlier, the chance of either gender is 50%.
I would suggest making some minor changes so that it follows the rules of genetics, such as 'how many cats will be such-and-such a color?'
It's true that cats are prone to wild color deviations, but if you make a teaser to conform to probabilites as they should work out, then I think that it's fine. I mean, if you truely tried to incorporate mutations into a teaser, you would not have a teaser at all, but an impossible problem.

I love your teasers, Swaff! I think that this one could also be really awesome with a few changes.

Sorry, you are wrong and I am sorry that so many people believed you and are going around thinking what you said is true. This would be true IF color was a sex-linked trait, which it is not. It does not matter the sex of the kitten because color is on autosomal chromosomes, meaning each kitten (male or female) will receive an allele from their mother and father. Sex of the kitten has nothing to do with color.

Actually, there is truth to the fact that sex and color being linked as in the case of calico and tortise-shell cats. Like RedPython said, there is a VERY small chance of a male tortie or claico, due to the linkage.

It's a pity that this site won't remove teasers that contain incorrect information. Hopefully, people will read the comments and learn something from these rather than just accept the incorrect answer given.